Stationary x-ray target and methods for manufacturing same
Stationary x-ray target assemblies manufactured using a metal deposition process to form one or more metal layers of the target. In particular, the metal deposition process is used to form an x-ray target metal layer and/or a stress buffer zone on an x-ray target substrate. The stress buffer zone improves material properties of the metals and/or the bonding between the x-ray target metal layer and the substrate. Improved bonding between the x-ray target metal layer and the substrate also improves the heat dissipation properties of the stationary x-ray target assembly.
1. A method for manufacturing a stationary x-ray target assembly, the method comprising:
providing an intermediate x-ray target assembly comprising a substrate; and
forming an x-ray target metal layer on at least a portion of the substrate using a electroforming process to yield a stationary x-ray target assembly,
wherein the x-ray target metal layer is comprised of at least one refractory metal suitable for generating x-rays upon impingement of a stream of electrons.
2. A method as in claim 1 , wherein the substrate is comprised of a material chosen from a group consisting of Cu, Mo, Ni, Fe, Ta, Re, W, Nb, V, Ir, Rh, Pt, Pd, stainless steel, and combinations thereof.
3. A method as in claim 1 , wherein the deposited x-ray target metal layer is comprised of one or more metals selected from the group consisting of Cu, Mo, Ni, Fe, Ta, Re, W, Nb, V, Ir, Rh, Pt, and Pd.
4. A method as in claim 1 , further comprising forming a buffer zone between the substrate and the x-ray target metal layer using an electroforming process, the buffer zone being comprised of one or more metals.
5. A method as in claim 4 , wherein the buffer zone comprises a graded composite or a graded alloy of two or more metals.
6. A method as in claim 4 , wherein the buffer zone comprises alternating layers of two or more metals.
7. A method as in claim 1 , wherein the stationary x-ray target assembly is comprised of copper and tungsten, and
wherein the substrate is comprised primarily of copper, the x-ray target metal layer is comprised primarily of tungsten, and including a buffer zone electroformed between the substrate and the x-ray target metal layer that is comprised of a composite of copper and tungsten, with the copper content being varied through at least a portion of the buffer zone.
8. A method for manufacturing a stationary x-ray target assembly using an electroforming process, comprising:
providing an electroforming apparatus, an electrolyte, a metal anode comprising a metal, and an electrically conductive cathode, the electrically conductive cathode comprised of at least one electrically conductive intermediate x-ray target assembly; and
forming a metal layer on at least a portion of the intermediate x-ray target assembly by electroforming of at least a portion of the metal from the anode onto the electrically conductive intermediate x-ray target assembly so as to yield a stationary x-ray target assembly,
wherein the metal layer is suitable for generating x-rays upon impingement of a stream of electrons on the stationary x-ray target assembly.
9. A method as in claim 8 , wherein the electrically conductive intermediate x-ray target assembly comprises one or more metals selected from the group consisting of Cu, Mo, Ni, Fe, Ta, Re, W, Nb, V, Ir, Rh, Pt, Pd, C, stainless steel, and combinations thereof.
10. A method as in claim 8 , wherein the metal anode of the electroforming apparatus comprises one or more metals selected from the group consisting of Cu, Mo, Ni, Fe, Ta, Re, W, Nb, V, Ir, Rh, Pt, and Pd.
11. A method as in claim 8 , further comprising electrodepositing a buffer zone between the intermediate x-ray target assembly and the metal layer by for coupling the intermediate x-ray target assembly to the metal layer.
12. A method as in claim 11 , wherein the metal anode comprises two or more metals and the buffer zone comprises a metal alloy or a metal composite.
13. A method as in claim 12 , wherein the metal alloy or the metal composite is graded.
14. A method as in claim 11 , wherein the metal anode comprises two or more metals and the buffer zone comprises alternating layers of the two or more metals.
15. A method as in claim 8 , wherein the electrolyte is a molten salt.
16. A method as in claim 8 , wherein the electroforming is carried out at a temperature greater than about 500 ° C.
17. An x-ray target assembly manufactured according to the method of claim 1 , thereby yielding an x-ray target assembly wherein the x-ray target metal layer has a substantially columnar microcrystalline structure and substantially 100% density.
18. An x-ray target assembly as in claim 17 , wherein the x-ray target metal layer has a thickness of at least 1.0 mm.
19. A stationary x-ray target assembly, comprising:
an x-ray target substrate comprising a first metal;
an x-ray target metal layer suitable for generating x-rays upon impingement of a stream of electrons comprising a refractory second metal; and
a buffer zone situated between the x-ray target substrate and the x-ray target metal layer, the buffer zone comprising a layered structure with alternating layers of the first and second metals, wherein the layered structure has layers of the second metal that gradually increase in thickness while simultaneously having layers of the first metal that gradually decrease in thickness.
20. A stationary x-ray target assembly as in claim 19 , wherein the buffer zone has thickness in a range from about 0.2 mm to about 3 mm.
21. A stationary x-ray target assembly as in claim 19 , wherein the buffer zone provides for substantially no thermal expansion mismatch between the x-ray target substrate and the x-ray target metal layer.